Numerous vinyl monomers possessing excellent reactivity toward free radical polymerizations are known and widely used throughout the industry for a variety of publications. Reactions involving these monomers can be initiated thermally, with chemical initiators, photochemically or using other forms of radiation, or by a combination of these methods.
In recent years increasing emphasis has been placed on the development of photocurable solventless coating and ink systems. Such systems are environmentally desirable since they do not require the use of organic solvents which often require special handling and ventilation and, upon evaporation, pollute the atmosphere. Also, since a simple light source is generally sufficient to cure such materials a substantial energy savings (50-80% reduction) can be realized compared to conventional oven curing. Additionally, photocurable systems are readily adaptable for use with heat-sensitive substrates, such as plastics, paper, cloth, etc.
Polyfunctional acrylates have typically been employed in photocurable coating and ink systems to enhance the rate of cure and provide the necessary film properties. While these acrylates are highly reactive and effective curing agents, they require special handling since they are highly irritating to the eyes, skin and mucous membranes and should not be inhaled in high concentrations. Work areas where these materials are employed must therefore be well ventilated. It would be highly desirable if monomers having reactivities similar to that obtained with the polyfunctional acrylates but without the aforementioned undesirable characteristics were readily available.